Method and apparatus for size reduction



Aug. 29, 1939. A MAXSQN 2,171,515

METHOD AND APPARATUS FOR SIZE REDUCTION Filed Aug. 29, 1936 .Zhvezzi'ar:

MAM.

Patented Aug. 29, 1939 UNITED STATES PATENT OFFICE METHOD AND APPARATUS FOR SIZE REDUCTION Massachusetts Application August 29, 1936, Serial No. 98,548

14 Claims.

My invention relates to methods of and apparatus for reducing or crushing materials, for example, coal, ores cement clinkers, and the like.

Among the purposes of my invention are an increase in efficiency of reduction and a minimum use of power for a given rate of size reduction. Another object of my invention is the provision of an improved apparatus in which the load undergoing reduction is, during the reducing cycle, subjected substantially constantly to reducing stresses or pressures. As an example, I oscillate or reciprocate a compact load of particles through a definite reducing zone and subject the load not merely to longitudinal reducing pressure at each change of direction of movement, but subject it to transverse reducing pressures intermediate said changes of movement, which pressures are occasioned by a continuous change in the form of the chamber within which the mass moves while the cross sectional area of the chamber is maintained substantially constant at all points be tween its end portions. Another object of my invention is the provision of an improved reduction apparatus in which between particle impact reductions the material undergoing processing is subjected to the joint, effects of centrifugal force and the constant size-reducing action produced by a substantially continuous change in the shape of the bounding walls which confine and guide the mass during its movements. A further object of my invention is to provide an improved size-reducing apparatus in which, while the load or charge is subjected to the several varieties of size-reducing forces above mentioned, including impact, centrifugally produced pressure, and positive rearrangement due to forced change in cross section of the mass, there is none the less provided an automatic control of feed in such manner that material enters the size-reducing chamber under the control of the material already therein, and new material is added only as material previously received in the size-reducing chamber is suflil clently reduced in size to escape therefrom through the discharge means provided. Yet another object of my invention is to provide an improved in had of sizereducing including as one feature th reof, and preferably in certain highly efllcient forms, the conjoint use of other size-reducing processes and enforced change in con-' formation of a mass of substantially constant cross sectional area so that there is a continuous working of the material mass within itself and of the particles thereof on each other. Still another object is to provide an improved method size-reduction'according to which variations power driven crank shaft I whose crank pin in the space relations of a reducing-chambers bounding walls cause a relatively continuous internal rearrangement and internal working of the chamber contents, whether said chamber be oscillated, reciprocated or rotated. As the varying cross section of the chamber enables thrust in the direction 'of chamber movement to be imparted to the contents without impacts at chamber ends, yet a further object is to provide improved means, whethen rotary, oscillatory, or reciprocatory, for causing chamber movements to cause internal working, in planes transverse to chamber movement, of contained material. Other objects and advantages of the invention will hereinafter more fully appear.

In the accompanying drawing, in which for purposes of illustration one illustrative embodiment of the invention has been shown, together with certain modifications thereof.

Fig. 1 is a central longitudinal vertical section through an apparatus in which certain structure phases of my invention are incorporated, and which operates according to certain of the method phases of my invention.

Fig. 2 is a radial section through the reducing chamber on the plane of the section line 2--2 of Fig. 1.

Fig. 3 is another radial section through the reducing chamber on the plane of the section line 3-3 of Fig. 1.

Fig. 4 is a further radial section through the reducing chamber and a portion of the feed neck, this section being taken on the plane of the section line 4-4 of Fi 1.

Figs. 5 and 6 are sections taken on planes intersecting each other at right angles and with their line of intersection extending centrally longitudinally through a size reducing chamber of a modified forma size-reducing chamber particularly adapted for rectilinear reciprocatory movement, certain parts being omitted.

Figs. '1, 8 and 9 are severally sections near chamber end, halfway between the chamber end and chamber center, and adjacent the chamber center, showing a further modified form of construction.

Referring first to Figs. 1 to 4 of the drawing, it will be observed that a frame H comprising a base I! and suitably spaced side elements l3 supports upon projecting portions l4 thereof '2 is connected by a pitman or connecting rod H with a size-reducing chamber generally designated 18. The crank shaft 15 is provided with a. combined driving pulley and flywheel 19 to which rotation may be transmitted through any suitable means, herein illustrated as a driving belt 1 to pivotal oscillation, may all be used in the practice of certain aspects of my invention. Herein, however, I have shown in Figs. 1 to 4, an oscillatory type of size-reducing chamber I8 which comprises, generally, a size-reducing chamber portion 2| and a feed-providing portion 22. The feed-providing portion 22 at its upper end is provided with pivot devices 23 supported in suitable bearing blocks 24 carried bythe side frame portions I3, and as the feed portion 22 suitably supports, herein by virtue of the integral construction, the size-reducing chamber portion 2 I, it will be evident that the size-reducing chamber, and indeed the entire size-reducing element I8, is pivotally supported for oscillatory movement about the axis of the pivots 23. A suitable pivotal connection 26 is arranged between ears 21, carried by one end of the chamber portion 2|, and the connecting rod l1. The upper end of the feed portion 22 is provided with an enlarged material-receiving mouth portion 28 so that the oscillation of the member l8 may not interfere with effective feed.

The size-reducing chamber portion 2| provides a chamber 30 so formed that a line midway between the upper and lower Surfaces thereof at all points throughout its length conforms substantially to an arc of a circle struck from the axis of the pivots 23. The cross sections of the chamber on planes passing through the pivot axes are of uniform area at all points, substantially, between the ends of the chamber, it being understood, of course, that at the extreme ends, which are preferably formed of a curvature somewhat as is shown at 32, the uniformity of cross sectional area is not ordinary, and that at the central portions of the chamber the cross section of the chamber proper must be distinguished from the combined cross section ofthe feed passage 33, formed within the feed portion 22, and

the chamber 30. Instead of employing uniformity of cross section in shape as well as in area, according to my invention the shape of the size-reducing chamber, that is, its cross sectional shape, is subjected to a considerable variation throughout the length of the chamber, although the cross sectional uniform. For example, in the chamber construction shown in Figs. 1 to 4, in which a generally rectangular cross section is adhered to at all points between the end portions of the chamber, the chamber may be in the form of a rec-- tangle considerably wider than it is high at the ends of the chamber, as, for example, at the section line 2-2; may be practically square at a point midway between the center and one of the ends of the chamber; and may be rectangular and considerably higher than it is wide at a point midway between the ends of the chamber. Again, as illustrated in Figs. 7, 8 and 9, where the chamber cross sections are in the form of conic sections, the chamber may be elliptical, with its X axis the shorter, at its ends; may be circular at points midway between the center and either end; and may be elliptical with the Y axis shorter adjacent the center portion thereof. The chamber is desirably provided with discharge orifices 35 which may be formed in a large number of different ways, as will be readily appreciated by area remains substantially course, within the contemplation of m invention.

A suitable chute and material catching structure for minimizing the escape of pulverized Inaterial is arranged as at 3B beneath the chamber element 2| and is connected vin'th a discharge passage 31 for. reduced material. Within the chamber there is provided normally, though not necessarily, a suitable size-reducing medium 38 which may assume the form of a considerable number of balls, or other shapes, of appropriately hard material and of graduated size so that stratification of the material in process and the size-reducing medium may be possible.

The feed passage 33 communicates with the size-reducing chamber 30 through a feed opening 40 whose elongation is suitably proportioned with respect to the overall length of the chamber and the overall range of oscillation of the chamber, so that the desired free play ofthe mass undergoing size-reduction with its intermingled charge of size-reducing media, where the latter are-used, may be attained. Depending upon the nature of the material-to be processed, the design Of the device will be modified to increase or diminish the part played by impact, it being obviously possible to have impact vary between a. maxium, a condition attained when the material enclosed within the chamber and the end portions of the chamber are moving oppositely to each other and both at maximum velocity at the instant of impact, and a much smaller value which may be reduced virtually to zero by appropriate control of the chamber length. As this feature of the invention of regulating chamber th to obtain a desired maximum intensity of impact is not broadly new with me, and as the feature of regulating the rate of admission of new material to be processed by the moving load within the chamber is also not broadly new with me, further detailed discussion of this subject matter is unnecessary.

With respect to the form of the invention so far described, it will be observed that the material awaiting entry into the chamber 30 and size-reduction therein, may be fed to the funnel, so-to-speak, 28, and allowed to stand as at 4| in the feed neck or connection 22 and rest upon the mingled material and size-reducing media mass 42 already in the chamber 30. As the crank shaft l5 rotates, the pitman I1 imparts through the pivot connection 26 a rapidly alternated oscillatory movement about the axis of the pivots 23 to the structure l8; and the material within the chamber is caused to surge from end to end of the chamber, traveling freely for a substantial fractionfor the proportions shown, perhaps forty percent-of the chamber length, out of contact with the end walls of the chamber. New material secures access to the space 30 only when the load within the chamber is compacted at either end of the latter, and then only through the. narrow space left, as indicated at F, at one end or the other of the compact load. During the oscillation of the member v|8 the chamber contents are subjected to impacts, to attrition during travel along the bottom wall of the chamber, and to internal working in a measure due to centrifugal force.

There is further, with my improved mill, however, provided a positive and virtually continuous rearrangement of the entire mass of material within the chamber, for longitudinal movement between the chamber and the material is impossible without a change in the cross section at all points between its length of the mingled mass of material and size-reducing media within the chamber. Take, for example, the portion of the material which is now adjacent the left hand end of the chamber in Fig. 1. This portion of the material is now spread horizontally so that it completely fills a cross section similar to the chamber cross section shown in Fig. 2. -As this particular portion of the chamber contents moves toward the right in Fig. 1, it is subjected by the bounding walls of the chamber 30 to a lateral constriction and to a vertical increase in dimension. This is naturally attended bya substantial crushing action on the material particles. By the time this quantity of material has moved to a position midway between its original location in the chamber and the center of the chamber, it will have been squeezed laterally while permitted to increase in dimension from top to bottom of the chamber sufficiently so that the cross section is a true square, and by the time this same portion of the-chamber contents attains a position substantially at the mid-point of the chamber length, it will have been further constricted laterally and increased in dimension vertically so that its cross section will resemble the cross section of the chamber shown in Fig. 4. Now, obviously, this process is going on virtually all the time that there is any relative movement between the chamber walls and the material within the chamber, and an extremely positive and effective size reduction, due to the forcible rearrangement of the larger particles during chamber oscillation, is assured.

As above pointed out, difierent forms of cross section may be'employed, and the effect described may be enhanced or diminished by altering the degreeof change in cross-sectional shape which occurs during the relative longitudinal movement between chamber charge and chamber proper. For example, by making a very wide and shallow cross section at the end, a very narrow and deep chamber cross section at the center, and an intermediate square section, a very intense action can be secured, but it is believed that ordinarily a more moderate change in the cross sectional area will promote a more effective size-reduction, in that a better combination of impact, attrition, and forced particle rearrangement at high velocities can be obtained by not cagyingjo extremes the feature of the forced rearrangement.

The chamber portion 2| may, of course,' be

provided with liners, if desired, and be of builtup construction, but these features are not illustrated as they fall within the knowledge of any skilled designer. A side opening permitting the removal of the ball charge and access to the interior of the chamber may be provided, as shown in Figs. 2, 3 and 4 at 44, a suitable side cover being provided normally to close the side open- While most desirable results are believed to be obtainable by the combination of the centrifugal effects and the positive variation in cross section illustrated generally in Fig. 1, it is obvious that it is unnecessary to employ a centrifugal component in certain forms of my invention. Example, Figs. 5 and 6 show, as above stated, longitudinal sectional views taken on planes at right angles to each other through a chamber construction per se which is suited for rectilinear reciprocation and which is not, bowed, as it were, between its ends. This form of chamber will be noted to have its central longitudinal line straight, and to have its ends of greater dimension in one'direction than in a direction at right angles to the first mentioned direction, to haveits center of a cross section of the same area as the end cross section but with the original shorter dimension now the longer and vice versa, and at points midway between the center and ends of the chamber to have the cross sectional area remain the same but the height and width of the chamber identical with each other, things simply being preferably arranged so that the cross sectional area at all points between the ends remains substantiallythe same. In Figs. 5 and 6 the chamber-forming element 2| is shown in horizontal section in Fig. 5 and in vertical section in Fig. 6, and has material-discharge orifices, herein in the form of slots 35, both in the side wall 5| thereof and in the bottom wall 52 thereof. The cross sections may, of course, be made rectangular or in the form of conic sections, or in other forms if that be preferred.

' In all of the forms of my invention shown it will be observed that there is present the feature of forcible rearrangement by continuous change in cross sectional shape of the size-reducing chamber at points along its line of movement, and accordingly it is submitted that a thoroughly effective size-reducing apparatus will be provided and that an effective mode--process--of size-reducing is provided.

While there are in this application specifically described one form and certain modifications of the same which my invention may assume in practice, it will be understood that this form and these modifications are shown for purposes of illustration and that the invention may be further modified and embodied in various other forms without departing from its spirit or the scope of the appended claims.

What I claim as new and desire to secure by Letters Patent is:

1. In a mill, means providing a size-reducing chamber supported for movement back and forth, said size-reducing chamber elongated in its direction of back-and-forth movement, of substantially uniform cross-sectional area throughout the major portion of its length but of varied cross-sectional shape at different points along its length, provided with discharge means through which material of small enough size may ass while the chamber is in motion, and having means for the introduction into said chamber during the operation of the mill of material to be processed, including a feed passage communicating with said chamber through an aperture inter mediate the ends of the chamber in a wall which extends longitudinally of the latter, and means for moving said chamber back and forth, said chamber of such dimension between said aperture and the opposite surface of said chamber, said chamber and saidaperture of. such relative lengths and disposition, said chamber having its bounding walls so formed, and said chambermovifig means imparting to said chamber movement at such rate and of such amplitude, that during normal continuous size-reducirr operation the chamber load will be reciprocated between the ends of the chamber as a substantially compact mass substantially filling the ent re cross-section of the chamber throughout the major portion of its own length but altering its 15 cross-sectional shape in its transit through said chamber, and sweeping across the feed aperture and controlling the ingress of material awaiting entrance to the chamber at said feed aperture, and coacting with said feed aperture to preclude the building up of the volume of the mass sufliciently to fill the chamber.

2. In a mill, means providing a reversely arcuately-moved chamber generally arcuate in its planes of movement and of substantially uniform cross-sectional area on planes including the axis of movement of such chamber at substantially all points between its'end portions but of varied cross-section in shape on different ones of said planes, said chamber having a feed connection terminating in an intake opening through a wall of said chamber and a charge of free size-reducing media in said chamber, said size-reducing media and material admitted through said feed opening forminga mass moving as a whole from end to end of said chamber and traveling alternately back and forth across said opening while said mill is in operation and acting as a gate therefor, and said mass undergoing deformation in cross section during its movement relative to said chamber.

3. In a reduction mill, a reducing chamber supported for oscillatory movement longitudinally about a pivot above the same, said chamber of upwardly-concave arcuate form in the planes of oscillation thereof, means for introducing material to be processed to said chamber in, the zone midway between the ends thereof, and means for varying the conformation of the chamber contents during oscillation of said chamber including means for subjecting the outer sides of said chamber contents during relative movement between the same andthe walls of said chamber to a constricting action altering the cross section of said contents.

4. In a reduction mill, a reducing chamber having therein during normal size-reducing operation a load sufiicient to fill at least one-half full the volume of said chamber but insuiiicient to fill the chamber from end to end, and means for. reciprocating the chamber, said reducing chamber elongated in its direction of reciprocation and of such length relative to its depth and width that the product of the greater of said last mentioned dimensions and its length is a plurality of times the product of its depth and width, and said reducing chamber being of substantially uniform cross sectional area throughout its length but also of substantially constantly varying cross sectional shape substantially throughout its length, and said means for reciprocating said chamber constructed and arranged to reciprocate the latter at such a rate and with such amplitude of movement that the chamber load is reciprocated between the chamber ends in a relatively compact mass substantially filling the cross section of said chamber throughout the major part of its own length and is subjected during such reciprocation to deformation of its cross sectional contour.

5. In a mill, means providing a size-reducing chamber supported for reciprocatory movement, said size-reducing chamber elongated in its direction of reciprocatory movement, of substantially uniform cross sectional area throughout the major portion of its length but varying smoothly and substantially in cross sectional shape along itslength, provided with discharge means for size-reduced material, and having feed ingress means between its ends having as- ,rocating means imparting to said sociated therewith supply means adapted to deliver material to said feed ingress means at a rate at least equal to the size-reducing capacity of the mill, and means for reciprocating said chamber, said chamber of such dimension normal to its path of reciprocation and said reciprocating means imparting to said chamber movement at such rate that the contents of said chamber are maintained substantially compact in a mass conforming to chamber cross sections, and said chamber and said feed ingress means of such lengths and relative disposition and said reciprocating means imparting to said chamber such movement that the chamber contents are maintained insuflicient completely to fill the chamber but sufficient to maintain said chamber substantially filled in cross section throughout at least one-half its length while maintaining simultaneously another portion thereof empty.

6. In a mill, means providing a size-reducing chamber supported for reciprocatory movement, said size-reducing chamber elongated in its direction of reciprocatory movement, of substantially uniform cross sectional area throughout at least the major portion of its length but varying substantially in cross sectional 'shape along its-length, provided with discharge means for size-reduced material efiective to discharge adequately reduced material while the chamber is in motion, having associated therewith supply means for material to be reduced, and having a feed opening between its ends with which said supply means communicates, and means for imparting to such chamber reciprocatory motion, said feed opening of such dimension longitudinally of said chamber relative to the overall chamber length and said chamber reciprocating means imparting to said chamber motion of such amplitude and at such speed that the chamber contents are caused to move as a relatively compact mass alternately with, and between the ends of, said chamber and to assume and maintain a volume adequate at least to fill the space within said chamber at one end of said feed opening and also substantially the entire space opposite said feed opening, while leaving a substantial unfilled space within said chamber, whereby, with material constantly maintained at and awaiting admission through said feed opening, relative reciprocation between the chamber contents and said chamber takes place and the chamber contents regulate the introduction of new material.

7. In a, mill, means providing a size-reducing chamber supported for reciprocatory movement, said size-reducing chamber elongated in its direction of reciprocatory movement, of substantially uniform cross sectional area throughout the major portion of its length but of substantially different cross sectional shape at different points between its ends, provided with discharge means for size-reduced material through which adequately reduced material may pass while said chamber is in motion, and having feed ingress means between its ends having associated therewith supply means adapted to deliver, while said chamber is in motion, material to said feed ingress means at a rate in excess of the size-reducing capacity-of the mill, and means for reciprocating said chamber, said chamber of such dimension between said feed ingress means and the opposite side of said chamber, said chamber and said feed ingress means of such relative lengths and disposition, and said chamber recipchamber movement of such rate and amplitude that with material constantly maintained at said ingress means and awaiting ingress to said chamber the chamber contents are maintained automatically, while said mill is in operation, sufliciently less in volume than the volume of said chamber so that relative reciprocation between said contents and said chamber may take place, but yet adequatein volume to occupy at least one-half the overall length of said chamber throughout its entire cross section, during normal mill operation.

8. In a mill, means providing a size-reducing chambersupported for swinging movement, said size-reducing chamber elongated in its direction of swinging movement and having upturned portions at opposite sides of its center as viewed from the side, of substantially uniform cross sectional area throughout at least the major portion of its length but of greater dimension normal to its arc of swing at one point along its length than at another and of greater width at the latter point than at the first, provided with discharge means for size-reduced material through which adequately reduced material may freely pass while said chamber is in motion, and having feed ingress means between its ends having associated therewith supply means adapted, while said chamber is in motion, to deliver material to said feed ingress means at a rate at least equal to the size-reducing capacity of the mill, said chamber having walls enclosing the same imperforate save for said discharge and feed ingress means, and means for oscillating said chamber through such an are that its ends are both always higher than an intermediate portion, said chamber of constantly varying dimensions though of uniform cross sectional area from end to end normal to its path of movement and of a length at least twice its maximum dimension normal to its path of movement, and the ratio of chamber length to the length, longitudinally of said chamber, of said feed ingress means and the rate of chamber oscillation such that the chamber contents are reciprocated in a substantially compact mass within said chamber in contact with and sustaining the head of material awaiting ingress to said chamber.

9. The method of size-reduction which includes maintaining a quantity of material to be reduced in an elongated body and reciprocating said body in a reduction zone of such length that both of the extremities of said body are out of contact with and spaced from the ends of said zone during the travel of said body in the central 5 portions of its path of reciprocation, and subjecting said body throughout its length, as it reciprccates, to changes in cross-sfitional shape while maintaining its cross-section substantially uniform in area.

10. A method according to claim 9, including the subjection of the body mentioned also to a centrifugally-produced transversely-acting pressure against a lateral wall of the reducing zone.

11. A method according to claim 9, including the subjection of the body mentioned to impacts at the opposite ends of the reduction zone in alternation.

12. The method of reducing material which includes reciprocating a substantially compact load, of which load material to be reduced forms at least a part, and which load is of a relatively predetermined length, in a reduction zone of substantially uniform cross-sectional area but of varying cross-sectional shape upon planes normal to the path of movement of said load, along a defined path of such length that said load may in an intermediate position be simultaneously spaced from each end of said zone, while maintaining the volume of the load such in relation to the cross-sectional area of said reduction zone that the latter is substantially filled throughout the length of said load when the load is in said position.

13. The method of reducing the size of material which includes maintaining in a reduction zone of a predetermined length and a lesser maximum height and of varying cross-sectional shape along its length but of substantially uniform cross-sectional area throughout at least the major portion of its length, a relatively compact load of which material to be reduced forms at least a part, and which load is of such length that free travel thereof in said zone is possible, and of such height that said zone is completely filled in cross-section throughout the centralv part thereof at all times, and causing reciprocation of said load in said zone, each pass of said load in said zone including a period of free bodily movement between the ends of the zone, terminating in an impact at an end of such zone.

14. In a mill, means providing a size-reducing I chamber supported for reciprocatory movement,

means for reciprocating said chamber, said chamber elongated in its direction of reciprocator'y movement, of substantially uniform cross sectional area throughout the major portion of its length but of constantly varying dimensions and having a greater dimension in one direction at a point equally spacedfrom its ends than the dimension of either end in the same direction, said chamber provided with discharge means for size-reduced material and with a feed connection terminating in an opening through a wall between the ends of said chamber and adapted to deliver material to said chamber during reciprocation thereof, said material forming a mass within said chamber and acting as a control for the feeding of material thereto.

LOUIS A. MAXSON. 

